Electrical disconnecting fitting



Aug. 4, 1936. R. T. ROTH 2,049,149

ELECTRICL DISCONNECTING FITTING Filed May 5l, 1950 2 Sheets-Sheet 2 IN VENT OR r A TTORNEY Patented Aug. 4, 1936 UNITED STATES PATENT OFFICE 10 Claims.

This invention relates to electrical disconnecting fittings such as may be used to connect a pot-head conductor or similar enclosed conductor with an aerial conductor. y

One object of my invention is to provide an improved fitting of this character, which is slmple and economical in construction, is composed of relativelyfew parts, which may be easily manipulated and where the operation of opening and closing the circuit may be effected at a minimum danger to the workmen employed. v

A furtherobject of my invention is to provide a fitting of this character with improved contacting elements which are adapted to be forced into engagement with one another to forma firm electrical connection for completion of the circuit through the fitting, which connection is not subject to accidental loosening. A further object is to provide an improved means for moving said contacts which means forms a protecting insulator enclosing said contact. A further object of my invention is to provide improved contact elements having main contacting faces or surfaces, together with auxiliary arcing surfaces, for protecting said main surfaces from destructive arcing when said contacts are separated.

Further objects and advantages of my invention will appear from the following description taken in connection with the accompanying drawings, wherein:

Figure 1 is a central longitudinal sectional view, partly in elevation, showing one form of my improved fitting with certain of the parts separated from one another to illustrate the way in which the contacts are moved to make and break the circuit,

Figure 2 is a view similar to Figure 1 showing the parts in closed position with the contacts in engagement with one another,

Figure 3 is a side elevation of the structure shown in Figure 1, l Figure 4 is a view similar to Figure 2 but showing a modification, and

Figure 5 is a similar view showing astill further modification.

hood nut I5 which may be screwed down against a gasket I6 to close the upper end of the bushing I 0. Screw threaded on the hood nut I5 is a lower contact which is adapted to be engaged by an upper movable contact |8.

Surrounding and partly enclosing the hood nut I5 and the upper end of the bushing I0 is a hollow locking member I9 formedv of bakelite or other similar insulating material. The locking member I9 fits loosely around the hood nut I5 l0 and, with the parts as shown in Figure l, is vcapa.- ble of a limited vertical movement and is free to rotate about the hood nut I5. The locking member I9 extends upwardly some distance above the contact and has molded into its inner wall, 15 some distance beneath its top, an internally screw threaded ring 2| which is adapted to be screwed onto the lower end of the upper contact I8 to force the upper contact down into engagement with the lower contact Il. During this opera- 20 tion the locking member I9 is held against upward movement by` engagement of an inwardly projecting portion 22 of the member I9 with the lower edge 23 of the contact I1. During the reverse operation of separating the contacts, any 25 downward thrust of the locking member is received against the upper surface 24 of the hood nut I5.

In the form of invention disclosed in Figure 1 the upper contact I8 is formed with a screw 30 threaded socket 25 for the reception of a conducting member or lug 21 which connects with an aerial cable. The construction shown lin Figure 2 is the same, except that I show a curved aerial lug 21 instead of the straight .lug 21 35 shown in Figure 1. Screw threaded to the upper portion of the contact I8 is a cap insulator 28 which extends downwardly around the upper part of the locking member I9.

As shown in Figures 1 and 2 the lower contact 40 I'I has its upper portion of frusto-conical shape, the outer conical surface 30 of which is adapted to engage an inner conical surface 3| of the up- .per contact I8. Also the lower contact I1 is formed with a central axial opening 33 adapted 45 to receive a split arcing and guiding pin 34 screw threaded into the upper contact at the center of the recess formed in the bottom of the upper contact. n

In the closed position of the parts, as shown in 50 Figure 2, it will be seen that the pin 34 projects a considerable distance into the opening 33. As the contacts are separated, the surface 3| of contact |8 leaves the surface 30 of contact I1, the parts moving to the position shown in Figure l from which will be seen that while the pin 34 is still in engagement with the edge of the opening 33, the main contact surfaces 30 and 3I have been separated a substantial distance. Further separation of the contacts results in complete breaking of the circuit at the lower end of the pin 34. The lower end of the pin 34 is tapered so that any arcing between the edge of the opening 33 and the pin 34 will occur at the tapered surface of the pin and not at the outer surface which slides in contact with the side of the opening 33. It will be seen from Figure 1 that in the closed position of the contact members there is a space between the upper surface of member I1 and the upper inner surface of member I8. Any injury to the former of these two surfaces will not interfere with the maintenance of a good current carrying contact between the members as reliance is had for the current carrying contact entirely on the conical surfaces of these mem'- bers. It is also to be noted that the upper contact assembly is supported so as to permit slight lateral movement of the upper contact as it moves toward the lower contact and the tapered surface at the end of the pin acts as a guide to center the upper contact for proper engagement with the lower contact.

The angle of inclination of the main contacting surfaces 30 and 3l to their axes is such as to pro- Vide a firm wedging and fitting engagement of the contacts with one another, without binding, and this angle is also such as to permit substantial separation of the surfaces before the connection is actually broken at the pin 34. I find that the angle shown or an angle of substantially 15 to 30 is satisfactory.

It is to be noted that the contacts themselves and the space between the contacts, as they are Separated to break the circuit, is entirely enclosed and protected by the cap insulator and locking member, thus permitting the manipulation of the contacts without danger of accidental contact with live parts.

In assembling the insulator the hood nut I5 is screwed in position as by means of a socket wrench engaging part 24 of the nut. 'I'he insulating locking member I9 is then placed over the hood nut and the lower contact screwed into posil tion on the hood nut. For this purpose the lower contact may be formed with openings 4| to receive a wrench for screwing it into position. The cap insulator 28 is screwed to the upper contact and the upper contact screwed to the lower end of the aerial lug 21 or 21' which is joined at its opposite end to the aerial cable. The 4upper contact as assembled is then moved down until the screw threaded ring ZI in the locking insulator engages the screw threads on the upper contact I8 when the insulator is turned to draw the upper contact down into engagement with the lower Contact.

While I have shown the contacts secured to the two cable terminals I2 and 2T of the types illustrated, it will be understood that cable terminals or lugs of other types may be employed and suitable means used for connecting the contacts thereto. When the fitting is employed with an electrical terminal stud, common for example in oil switches, the lower contact may be mounted directly on the stud and in which case a yhood nut need not be employed. I have shown such a construction in Figure 5 wherein the contact Il is mounted on the terminal stud 31. In the construction shown in this figure, a lock nut 38 screwed down against the insulating tube 39,

forms a support for the locking member I9 when the fitting is open.

In Figure 4 I show a modification wherein the lower contact and hood nut are made in one piece indicated at 40. In this construction in order to provide a stop to prevent upward movement of the locking member as it is being ro- .tated to close the contacts, I may provide a reconnected with one contact and having a metal portion adapted for screw threaded engagement with the other contact, whereby on rotation of said insulator in one direction or the other, said contacts are brought together or separated, said metal portion being spaced from one contact "f whereby current in passing from one contact to the other does not pass through said metal portion.

2. In an electrical disconnecting fitting, a stationary contact having a conical contacting sur- L face, a movable contact having a conical contacting surface adapted for fitting engagement with said rst named surface and means for moving said contacts toward and away from one another, said means comprising a locking insulator surrounding said contacts, said insulator being rotatably connected to said stationary contact and having an interior ring rigid therewith adapted for screw threaded engagement with said movable contact, said ring being spaced from said stationarypontact.

3. In a disconnecting fitting, a hood nut adapted to receive a cable terminal and formed with an outwardly extending bottom flange, a contact member screw threaded to the top of said nut, a rotary locking insulator having a portion held between said contact and flange, a second contact adapted to engage said first named contact, said locking insulator having a portion spaced from said first named contact and adapted for screw threaded engagement with said second contact for moving said contacts toward I and away from one another.

4. In combination a pot head insulator havterminal extending through the restricted portion of said opening and having projections bear-l ing against the sides of the opening, a cap nut screw threaded on the end of the terminal and having a flange bearing against an end of said insulator and. cooperating with said projections to secure said terminal firmly in said insulator, a conducting member surrounding and screw threaded to said cap, a second insulator surrounding said cap and rotatably held between said flange and member, a second contact adapted for engagement with said first named contact and means connecting said second insulator with said second contact whereby movement of said second insulator moves the second contact toward or away from said first named contact.

5. In ycombination a pot head insulator having an opening therein restricted at one end, a terminal extending through the restricted portion of said opening and having projections bearing against the sides of the. opening, a cap nut screw threaded on the end of the terminal and having a flange bearing against an end of said insulator and cooperating with said projections to secure said terminal firmly in said insulator, a contactscrew threaded onto said cap, a rotary locking insulator having a portion held between said contact and flange, a second contact adapted to engage said firstnamed contact and said locking insulator having a portion adapted for screw threaded engagement with said second contact for moving said contact members toward and away from one another.

. 6. In a disconnecting fitting, two cooperating contacts formed of rigid material, one of substantially irusto conical form and the other having a substantially frusto conical opening, said contacts being adapted for fitting engagement with one ,another with their conical surfaces in facial contact and with the outer end face of the frusto conical contact spaced from the bottom of the frusto conical opening, one of said contacts having an opening and the other having an arcing pin adapted to nt into the latter opening, the axis of the latter opening and -pin being located inside the conical surfaces and means for inserting said pin in said latter opening and moving said surfaces together and for withdrawing said pin from said opening and for separating said surfaces.

7. In a disconnecting fitting, two cooperating contacts formed of rigid material, one of substantially frusto conical form and the other having a substantially frusto conical opening, said contacts being adapted for fitting engagement with one another with their conical surfaces in facial contact and with the outer end face `of .the frusto conical contact spaced from the bottom of the frusto conical opening, one of said contacts having an opening and the other hav- V.ing an arcing pin adapted to fit into the latter opening, the axis ofl the latter opening and pin being located inside the conical surfaces and means for inserting said pin in said latter opening and moving said surfaces together and for withdrawing said pin from said opening and for separating said surfaces, said means comprising a member swiveled to one contact and having screwthreads engaging the other contact and having insulating material supporting the screw- 5 threads from said one contact whereby current flowing between the contactdoes not flow through said threads. g

8. In a disconnecting iitting, two cooperating contacts formed of rigid material, one of sub- 1o stantially frusto conical form and the other having substantially a frusto conical'opening, said contacts being adapted for fitting engagement one with an other and their conical surfaces in facial contact and the outer end. face of the 15 frusto conical contacts spaced from the bottom of 'the frusto conical opening, an arcing pin extending axially from the bottom of the conical opening and the frusto conical contact having an opening therein into which the pin is adapted 20 to fit and means for inserting said pin in said latter opening' and moving said surfaces together and for withdrawing said pin from said opening and from separating said surfaces.

9. In combination, a pothead having a termi- 25 nal extending outwardly from one end thereof,

a contact secured to and extending around the outer end of the terminal, a rotatable locking insulator held between said end of the pothead and said contact, a second contact and 30 means between the second contact and insulator whereby on movement of said insulator the second contact is moved toward or away from said rst named contact.

10. In combination, a pothead having a ter- 35 minal extending outwardly from one end thereof, a contact screwthreaded over the outer end of the terminal, a rotatable locking insulator held between said end of the pothead and said contact, a second contact and means between 0 the second contact and insulator whereby on movement of said insulator the second contact is moved toward or away from said first named contact.

RAYMOND T. ROTH. 45 

